Modular type indicator unit



March 15, 1966 F". A. HARRINGTON ETAL 3,241,135

MODULAR TYPE INDICATOR UNIT Filed Oct.

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INVENTORS'.

United States Patent 3,241,136 MODULAR TYPE INDICATOR UNIT Frank A.Harrington, Brea, Thomas S. Jentges, Orange,

and Donald V. Hanzich, Garden Grove, Calif., assignors to Marco OakIndustries, a corporation of California Filed Oct. 7, 1963, Ser. No.314,472 4 Claims. (Cl. 340--381) This invention relates to indicatorlight units of the modular type, adapted to be grouped in vertical tiersand/ or horizontal rows, each unit embodying a rectangular case having afront opening that is relatively long and narrow, and a lamp holder thatis correspondingly long and narrow, having an indicator lens or windowbearing a suitable indicator legend of one or more words, the holdernormally being disposed in the front opening of the casing, but beingremovable therefrom (as by swinging on a hinge-at one end) for servicingaccess to the back of the holder, for replacement of lamps mounted insockets in the back of the holder.

The object of the present invention is to provide an improved backcontact assembly for establishing a common connection to the endcontacts of the lamps.

An important object is to provide a spring-loaded engagement between acommon contact and two spaced lamp contacts, with balanced springloading at both contact points.

A particular object is to provide a back contact assembly of simplifiedconstruction and reduced fabrication cost. Accordingly, the inventioncontemplates a back contact assembly of stamped ribbon metal parts,adapted to establish balanced springdoaded contact simultaneously withthe end contacts of two laterally spaced lamps.

Other objects will become apparent in the ensuing specification andappended drawing, in which:

FIG. 1 is a plan view of an indicator unit embodying the invention withcentral portions thereof broken away and shown in section;

FIG. 2 is a front elevational view of the improved back contactassembly, with parts broken away and shown in section, as indicated online 22 of FIG. 1; and

FIG. 3 is a perspective view of the back contact assembly.

Referring now to the drawing in detail, I have shown therein, as anexample of one form in which the invention may be embodied, a modulartype indicator unit comprising, in general a rectangular casing A ofsubstantial depth from front to rear as seen in FIG. 2; and a lampholder and lamp assembly B which is normally disposed within the casingA in closing relation to a front opening therein, and which has one endthereof hinged at 11 to casing A in one end of opening 10, and its otherend normally latched to casing A by a latch 12 which is spring-loadedtoward latched position and released by a push bar 13. Latch 13 latchesagainst the end of a bus bar 14 on the back of holder B and constitutesone of several series connections (also including a bus bar 12) betweena terminal post 15 mounted in the back 16 of casing A, and a pair oflamp sockets 17 formed in bus bar 14. Lamps 18 are mounted in sockets17, within the holder B, which is in the form of a deep tray. Thelatched end of holder B can be depressed by finger tip pressure toestablish a test circuit to lamps 18 by engaging bus bar 14 against atest contact post 19. A return spring 20 yieldingly biases the holder Boutwardly for engagement with latch 12. This arrangement of parts isdescribed more fully in US Patent No. 2,916,725, issued December 8,1959, to C. W. Noyes.

The improved back contact assembly of the present invention comprises,in general, a back contact C, a bracket D, and a coil spring 25. ContactC, of yoke form, comprises a bridge bar 26, a pair of fingers 27 bent atright angles from respective ends of bar 26 and projecting rearwardly,and claws 28 projecting laterally inwardly from the rear ends of fingers27. In the center of bar 26 is a spring pilot 29, punched or embossedrearwardly and extending into the forward end of spring 25. Bracket D,also of yoke form, comprises a base 30, a pair of arms 31 bent forwardlytherefrom, and a pair of stops 32 bent outwardly from the forward endsof arms 31 forwardly of the claws 28, in overlapping relation thereto.Bracket D is secured to the back 16 of casing A by means of a terminalpost 33 which extends through the back 16 and through the bracket base30 and has a head 34 riveted against base 30 to secure it to back 16.Head 34 is piloted in the rear end of spring 25. Spring 25 is retainedby head 34 and pilot 29.

Spring 25 is engaged under compression between the center of contact bar26 and bracket base 30 and springloads the contact C so that itsrespective ends make equalized yielding engagement with the contacts ofrespective lamps 26, the claws 28 being slightly spaced from stops 32,and the contact C being in a floating condition. This occurs when theholder B is in its normal latched position shown in full lines inFIG. 1. When the holder B is unlatched and tilted out of the opening 10as indicated in phantom in FIG. 1, the contact C will follow the lamps18 forwardly until stopped by engagement of the claws 28 against stops32, and will be held there by spring pressure until the holder B isreturned to its latched position.

We claim:

1. In a modular type indicator unit, in combination: an elongated casingincluding a back wall and a front opening; an elongated lamp holdernormally received in and closing said front opening and removabletherefrom for servicing, said holder including a back having a pair oflamp sockets spaced along the length thereof; a pair of lamps mounted insaid sockets and having side contacts and end contacts; means providinga connection through said sockets to side contacts of said lamps; a backcontact in the form of a yoke including a current conducting barnormally bridging between and engaged by the end contacts of said lamps,a pair of fingers composite with and extending rearwardly from the endsof said bridging bar and having at their rear ends respective hooksprojecting laterally therefrom generally parallel to said bar; a bracketof yoke form including a current conducting base attached to said casingback wall, a pair of arms projecting forwardly from said base past therear ends of respective fingers of said back contact, and stops on theends of the respective arms, projecting transversely therefrom forwardlyof said hooksin overlapping relation thereto; a spring engaged undercompression between said base and said bridging bar and normallypressing said back contact into yielding engagement with said endcontacts of the lamps while establishing and maintaining electricalconnection between said bracket and said back contact, said hooksengaging said stops to limit the spring-loaded forward projection ofsaid back contact when said lamp holder is removed forwardly from saidopening; and terminals connected respectively to said bracket base andto said sockets.

2. An indicator unit as defined in claim 1, wherein the terminal forsaid bracket embodies a post extended through said casing back and saidbracket base and having a head engaging the inner side of said base, andwherein said spring is a coil spring having one end piloted over saidhead and seated against said base.

3. An indicator unit as defined in claim 2, wherein said bridging barhas an integral pilot projection struck rearwardly from the centerthereof and piloted in the other end of said spring.

4. An indicator unit as defined in claim 1, wherein said bracket armsare embraced between said back contact fingers, said hooks projectinwardly and said stops project outwardly.

References Cited by the Examiner UNITED STATES PATENTS Rowe 339255Attwood 24259 X Kruger 339--255 X Greenlee et a1 340281 Noyes 340366Noyes 340-366 Robbins 339254 X NEIL C. READ, Primary Examiner.

1. IN A MODULAR TYPE INDICATOR UNIT, IN COMBINATION: AN ELONGATED CASINGINCLUDING A BACK WALL AND A FRONT OPENING; AN ELONGATED LAMP HOLDERNORMALLY RECEIVED IN AND CLOSING SAID FRONT OPENING AND REMOVABLETHEREFROM FOR SERVICING, SAID HOLDER INCLUDING A BACK HAVING A PAIR OFLAMP SOCKETS SPACED ALONG THE LENGTH THEREOF; A PAIR OF LAMPS MOUNTED INSAID SOCKETS AND HAVING SIDE CONTACTS AND END CONTACTS; MEANS PROVIDINGA CONNECTION THROUGH SAID SOCKETS TO SIDE CONTACTS OF SAID LAMPS; A BACKCONTACT IN THE FORM OF A YOKE INCLUDING A CURRENT CONDUCTING BARNORMALLY BRIDGING BETWEEN AND ENGAGED BY THE END CONTACTS OF SAID LAMPS,A PAIR OF FINGERS COMPOSITE WITH AND EXTENDING REARWARDLY FROM THE ENDSOF SAID BRIDGING BAR AND HAVING AT THEIR REAR ENDS RESPECTIVE HOOKSPROJECTING LATERALLY THEREFROM GENERALLY PARALLEL TO SAID BAR; A BRACKETOF YOKE FORM INCLUDING A CURRENT CONDUCTING BASE ATTACHED TO SAID CASINGBACK WALL, A PAIR OF ARMS PROJECTING FORWARDLY FROM SAID BASE PAST THEREAR ENDS OF RESPECTIVE FINGERS OF SAID BACK CONTACT, AND STOPS ON THEENDS OF THE RESPECTIVE ARMS, PROJECTING TRANSVERSELY THEREFROM FORWARDLYOF SAID HOOKS IN OVERLAPPING RELATION THERETO; A SPRING ENGAGED UNDERCOMPRESSION BETWEEN SAID BASE AND SAID BRIDGING BAR AND NORMALLYPRESSING SAID BACK CONTACT INTO YIELDING ENGAGEMENT WITH SAID ENDCONTACTS OF THE LAMPS WHILE ESTABLISHING AND MAINTAINING ELECTRICALCONNECTION BETWEEN SAID BRACKET AND SAID BACK CONTACT, SAID HOOKSENGAGING SAID STOPS TO LIMIT THE SPRING-LOADED FORWARD PROJECTION OFSAID BACK CONTACT WHEN SAID LAMP HOLDER IS REMOVED FORWARDLY FROM SAIDOPENING; SAID TERMINALS CONNECTED RESPECTIVELY TO SAID BRACKET BASE ANDTO SAID SOCKETS.